From January to May, the profits of China's industrial companies declined 2.4 percent, despite an 11.9 percent growth in revenue in the same period, suggesting a declining profit margin, according to the National Statistics Bureau.

In May, the profit of industrial companies decreased 5.3 percent over last month to reach 390.9 billion yuan ($61.88 billion).

In 2011, the profit growth rate was 1.8 percentage points?lower than the revenue growth rate. That gap widened to 14.3 percentage points in the first five months of 2012, the data showed.

The index only included companies with annual revenues of more than 20 million yuan.

Among the industrial sectors, the ferrous metals smelt sector saw the largest drop with 56.9 percent, followed by chemicals with 23 percent and power generation with 22.2 percent.